KR20170013105A - Coating method of seperator for fuel cell and seperator for fuel cell - Google Patents

Abstract

The present invention relates to a method for coating a separation plate for fuel cells, and a separation plate for fuel cells, capable of minimizing transformation of a base material by forming a coating layer at a low temperature. According to an embodiment of the present invention, the method for coating a separation plate for fuel cells comprises the following steps: producing precursor gas by vaporizing a precursor; introducing the precursor gas and reactive gas into a reaction chamber; and forming the coating layer on the base material by converting the precursor gas and the reactive gas into a plasma state after application of voltage to the reaction chamber.

Description

TECHNICAL FIELD [0001] The present invention relates to a method of coating a separator for a fuel cell and a separator for a fuel cell,

A method for coating a separator for a fuel cell, and a separator for a fuel cell.

Fuel cell stacks consist of repeatedly stacked parts such as electrode films, separator plates, gas diffusion layers and gaskets, fastening mechanisms for fastening the stack modules, enclosures to protect the stack, components needed for interfacing with the vehicle, And so on. The fuel cell stack is a device in which hydrogen reacts with oxygen in the air to release electricity, water, and heat. The fuel cell stack has many risk factors as high voltage electricity, water, and hydrogen coexist in the same place.

Particularly, in the case of a fuel cell separator, the hydrogen cations generated during the operation of the fuel cell are in direct contact with each other, and therefore, resistance to corrosion is further required. In addition, corrosion of the metal during the application of the metal separator without surface treatment, Acts as an electrical insulator and lowers electrical conductivity. At this time, dissociated metal cations contaminate the membrane electrode assembly (MEA), thereby reducing the performance of the fuel cell.

In the case of a carbon-based separator used as a fuel cell separator, there is a large risk that a crack generated in the process will remain in the fuel cell, and it is difficult to reduce the thickness in terms of strength and gas permeability.

On the other hand, the metal separator is advantageous in terms of formability and productivity due to its excellent ductility, and it is possible to make the stack thinner due to its thinness. However, due to contamination of the MEA due to corrosion and increase in contact resistance due to surface oxide formation, . Therefore, there is a need for a surface treatment method capable of suppressing surface corrosion and oxide film growth.

One embodiment of the present invention is to provide a method of coating a separator plate for a fuel cell.

Another embodiment of the present invention is to provide a separator plate for a fuel cell.

Yet another embodiment of the present invention is to provide a precursor for a separator plate for a fuel cell.

According to an embodiment of the present invention, there is provided a method of coating a separator for a fuel cell, comprising: precursor gas is produced by vaporizing a precursor; Introducing the precursor gas and the reactive gas into a reaction chamber; And applying a voltage to the reaction chamber to change the precursor gas and the reactive gas into a plasma state to form a coating layer on the base material.

The precursor may include a compound represented by the following general formula (1).

[Chemical Formula 1]

Wherein R ¹ to R ⁸ are each independently a substituted or unsubstituted C 1 to C 10 alkyl group wherein N is nitrogen wherein Me is Ti, Cr, Mo, W, Cu, or Nb.

The precursor may further comprise a compound represented by the following general formula (2)

The compound represented by Formula 1 and the compound represented by Formula 2 may be different.

(2)

Wherein R ⁹ to R ¹⁶ are each independently a substituted or unsubstituted C1 to C10 alkyl group wherein N is nitrogen and Me is Ti, Cr, Mo, W, Cu, or Nb.

The R ¹ to R ⁸ may all be a methyl group (CH ₃ ).

The step of forming the coating layer on the base material may be performed at a temperature range of 200 ° C or less.

The step of vaporizing the precursor to produce the precursor gas may be performed at a temperature ranging from 50 to 80 캜.

The reactive gas may be a hydrocarbon gas; Inert gas; And a nitrogen compound gas or a nitrogen gas.

The hydrocarbon gas may be a material selected from C ₂ H ₂ , CH _4, or a combination thereof, the inert gas may be Ar, and the nitrogen compound may be NH ₃ .

Further, the method may further include the step of applying a hydrophobic group or a hydrophilic group after the step of forming the coating layer on the base material by changing the precursor gas and the reactive gas into a plasma state.

The step of imparting the hydrophobic group or the hydrophilic group may be a step of applying a gas selected from the group consisting of CF ₄ , O ₂ , CO ₂ , polydimethylsiloxane (PDMS), trimethylsilyl (TMS) And reacting F, O, Si, or a combination thereof on the surface of the coating layer.

The separation plate for a fuel cell according to an embodiment of the present invention includes a separation plate for a fuel cell and a coating layer disposed on one or both surfaces of the separation plate for the fuel cell, The coating layer may include carbon having an SP2 structure; And a nitride of a material selected from Ti, Cr, Mo, W, Cu, Nb, or combinations thereof.

The coating layer may be a nitride of a material selected from the group consisting of Ti, Cr, Mo, W, Cu, Nb, or combinations thereof, with the content of carbon having SP2 structure being 40% to 70%.

The thickness of the coating layer may be 20 nm to 1000 nm.

The coating layer may further comprise a material selected from the group consisting of F, O, Si, or a combination thereof.

The precursor for a fuel cell separator according to an embodiment of the present invention may include a compound represented by the following general formula (1).

[Chemical Formula 1]

Wherein R ¹ to R ⁸ are each independently a substituted or unsubstituted C 1 to C 10 alkyl group wherein N is nitrogen wherein Me is Ti, Cr, Mo, W, Cu, or Nb.

The precursor may further include a compound represented by the following general formula (2), wherein the compound represented by the general formula (1) and the compound represented by the following general formula (2) may be different.

(2)

Wherein R ⁹ to R ¹⁶ are each independently a substituted or unsubstituted C1 to C10 alkyl group wherein N is nitrogen and Me is Ti, Cr, Mo, W, Cu, or Nb.

The R ¹ to R ⁸ may all be a methyl group (CH ₃ ).

According to one embodiment of the present invention, the coating layer can be formed at a low temperature, and the deformation of the base material can be minimized.

According to one embodiment of the present invention, a coating layer can be formed at a low temperature, thereby reducing manufacturing costs.

According to one embodiment of the present invention, a coating layer can be formed by a PECVD process, and a coating layer can be formed even in a large area.

1 is a schematic view showing a plasma enhanced chemical vapor deposition (PECVD) apparatus for forming a coating layer on a separator plate for a fuel cell according to an embodiment of the present invention.
2 is a graph showing the contact resistance and the corrosion current according to the temperature condition of the reaction chamber in the embodiment.
3 is a photograph showing the surface of the separator coated according to the respective deposition temperatures.
4 is a schematic view for explaining a method of measuring the contact resistance of the separator-separator plate.
5 is a schematic view for explaining a method of measuring the contact resistance of the GDL-separator plate.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention, and the manner of achieving them, will be apparent from and elucidated with reference to the embodiments described hereinafter in conjunction with the accompanying drawings. However, it is to be understood that the present invention is not limited to the disclosed embodiments, but may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. It is intended that the disclosure of the present invention be limited only by the terms of the appended claims. Like reference numerals refer to like elements throughout the specification.

Thus, in some embodiments, well-known techniques are not specifically described to avoid an undesirable interpretation of the present invention. Unless defined otherwise, all terms (including technical and scientific terms) used herein may be used in a sense commonly understood by one of ordinary skill in the art to which this invention belongs. Whenever a component is referred to as "including" an element throughout the specification, it is to be understood that the element may include other elements, not the exclusion of any other element, unless the context clearly dictates otherwise. Also, singular forms include plural forms unless the context clearly dictates otherwise.

As used herein, unless otherwise defined, "substituted" means a C1 to C30 alkyl group; C1 to C10 alkylsilyl groups; A C3 to C30 cycloalkyl group; A C6 to C30 aryl group; A C2 to C30 heteroaryl group; A C1 to C10 alkoxy group; A C1 to C10 trifluoroalkyl group such as a fluoro group and a trifluoromethyl group; Or cyano group.

In the present specification, the term "combination thereof" means that two or more substituents are bonded to each other via a linking group or two or more substituents are condensed and bonded.

As used herein, unless otherwise defined, the term " alkyl group "means a" saturated alkyl group "which does not include any alkene or alkynyl group; Or an "unsaturated alkyl group" comprising at least one alkene group or alkyne group. Means a substituent in which at least two carbon atoms are composed of at least one carbon-carbon double bond, and "alkynyl group" means a substituent in which at least two carbon atoms are composed of at least one carbon-carbon triple bond . The alkyl group may be branched, straight-chain or cyclic.

The alkyl group may be a C1 to C20 alkyl group, more specifically a C1 to C6 lower alkyl group, a C7 to C10 intermediate alkyl group, or a C11 to C20 higher alkyl group.

For example, C1 to C4 alkyl groups mean that from 1 to 4 carbon atoms are present on the alkyl chain, which includes methyl, ethyl, propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl and t- Indicating that they are selected from the group.

Typical examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a t-butyl group, a pentyl group, a hexyl group, an ethenyl group, a propenyl group, a butenyl group, a cyclopropyl group, Pentyl group, cyclohexyl group, and the like.

1 is a schematic view showing a plasma enhanced chemical vapor deposition (PECVD) apparatus for forming a coating layer on a separator plate for a fuel cell according to an embodiment of the present invention.

Referring to FIG. 1, a PECVD apparatus used in an embodiment of the present invention includes a reaction chamber 10 maintained in a vacuum and capable of forming a plasma therein, and a reactive gas, a precursor gas, and the like, Gas supply device.

A vacuum pump 11 for forming a vacuum in the chamber is connected to the reaction chamber 10 and a base material (separation plate) is disposed between the electrodes 11 installed in the reaction chamber 10. When the power is supplied from the power supply 12, the gases inside the reaction chamber are changed to a plasma state. The gases in the plasma state are polymerized and coated on the surface of the base material 20.

First, a precursor gas is produced by vaporizing a precursor.

The precursor may include a compound represented by the following general formula (1).

[Chemical Formula 1]

Wherein R ¹ to R ⁸ are each independently a substituted or unsubstituted C 1 to C 10 alkyl group wherein N is nitrogen wherein Me is Ti, Cr, Mo, W, Cu, or Nb.

The precursor may further comprise a compound represented by the following general formula (2)

The compound represented by Formula 1 and the compound represented by Formula 2 may be different.

(2)

Wherein R ⁹ to R ¹⁶ are each independently a substituted or unsubstituted C1 to C10 alkyl group wherein N is nitrogen and Me is Ti, Cr, Mo, W, Cu, or Nb.

The R ¹ to R ⁸ may all be a methyl group (CH ₃ ).

The precursor can be vaporized at 50 DEG C or higher. When the precursor temperature exceeds 80 ° C, the characteristics of the precursor can be deformed by heat.

The precursor gas and the reactive gas are introduced into the reaction chamber.

The reactive gas may be a hydrocarbon gas; Inert gas; And a nitrogen compound gas or a nitrogen gas.

The hydrocarbon gas is a material selected from C ₂ H ₂ , CH _4, or a combination thereof, the inert gas is Ar, and the nitrogen compound may be NH ₃ .

When the precursor gas and the reactive gas are introduced into the reaction chamber, a voltage is applied to the reaction chamber to change the precursor gas and the reactive gas into a plasma state. The gas changed into the plasma state is deposited on the surface of the base material and polymerized and coated.

At this time, the step of forming the coating layer on the base material may be performed at a temperature range of 200 ° C or lower. When deposited above 200 ° C, contact resistance and corrosion current can be increased.

The lower limit of the temperature range in the step of forming the coating layer on the base material is not particularly limited. However, when deposited at less than 100 캜, the vaporized precursor may condense or the decomposition of the precursor may be incomplete and the contact resistance may rise.

Further, in the step of forming the coating layer on the base material, the pressure of the reaction chamber may be 0.01 to 10 Torr.

If the pressure in the reaction chamber is less than 0.01 Torr, the amount of decomposed ions may be small and the deposition rate may be lowered. If the pressure is more than 10 Torr, the adhesion may be lowered.

In addition, in the method of coating a separator for a fuel cell according to an embodiment of the present invention, a step of providing a hydrophobic group or a hydrophilic group after forming the coating layer on the base material by changing the precursor gas and the reactive gas into a plasma state .

The step of adding the hydrophobic group or the hydrophilic group may be performed by changing a gas selected from the group consisting of CF ₄ , O ₂ , CO ₂ , polydimethylsiloxane (PDMS), trimethylsilyl (TMS) To react F, O, Si, or a combination thereof on the surface of the coating layer.

The separator for a fuel cell according to an embodiment of the present invention includes a separator for a fuel cell and a coating layer on one or both sides of the separator for the fuel cell, The coating layer may include carbon having an SP2 structure; And a nitride of a material selected from Ti, Cr, Mo, W, Cu, Nb, or combinations thereof. The SP2 structure is a structure in which one carbon is bonded to three carbons present on the same plane on the periphery.

Here, the content of carbon having an SP2 structure based on 100 atomic% of the entire coating layer may be 40 to 70 atomic%. And more specifically 50 to 70 atomic%. Further, when Ti nitride is contained in the coating layer, Ti present in the coating layer may be 30 atomic% or more.

The thickness of the coating layer may be 20 nm to 1 mm. More specifically, it may be 1 mu m or less.

When the thickness of the coating layer is less than 20 nm, the corrosion resistance may be lowered. When the thickness exceeds 1 mm, more specifically, when the thickness exceeds 1 m, the conductivity may be lowered.

In addition, the coating layer may further comprise a material selected from the group consisting of F, O, Si, or a combination thereof.

Hereinafter, the embodiment will be described in detail. The following examples are illustrative of the present invention only and are not intended to limit the scope of the present invention.

<Examples>

A precursor containing the compound represented by the following general formula (3) was heated at 50 캜 and vaporized to prepare a precursor gas.

(3)

The precursor gas, C ₂ H ₂ , NH ₃ , and Ar was injected into the reaction chamber.

Subsequently, a voltage was applied to the reaction chamber to change the gases to a plasma state and to deposit them on the base material. SUS316L, which is defined in JIS standard, was used as the base material. During the formation of the coating layer, contact resistance and corrosion current at 0.6 V were measured by varying the temperature conditions of the reaction chamber. The pressure in the reaction chamber was 0.8 Torr and RF power of 1500 W was applied.

The results of the experiment are shown in FIG. 2 and Table 1.

Deposition temperature Contact resistance Corrosion current (° C) (m? cm ² ) (㎂ / ㎠) 0 308.4 9.2 50 132.3 7.4 100 79.9 3.4 150 34.8 2.1 200 41.7 2.6 300 280.1 14.2 400 981.3 72.4

The contact resistance was measured in the following manner.

4 is a schematic view for explaining a method of measuring the contact resistance of the separator-separator plate.

First, place the one separating plate between the plated Au entire house as shown in (a) of Figure 4, and by applying pressure of 10kgf / cm ² measuring resistance (R1, mΩ). Thereafter, as shown in Fig. 4 (b), two separators are disposed between the current collectors and the resistances (R2, m?) Are measured under the same conditions.

The contact resistance (mΩ · cm ² ) of the separator-separator was calculated as (R2-R1) * separator area.

5 is a schematic view for explaining a method of measuring the contact resistance of the GDL-separator plate.

First, three gas diffusion layers (GDL) are disposed between Au-plated current collectors as shown in FIG. 5A, and a pressure of 10 kgf / cm ² is applied to measure a resistance (R3, m?). As the gas diffusion layer (GDL), 10BB of SGL was used as the porous carbon material.

Then, four gas diffusion layers (GDL) are disposed between current collectors as shown in FIG. 5 (b), one separator plate is disposed in the middle of the gas diffusion layers GDL, and the resistances R4 and mΩ are measured under the same conditions.

The contact resistance (mΩ · cm ² ) of the GDL-separator was calculated as (R4-R3) * separator area.

The contact resistance of the separator-separator plate and the contact resistance of the GDL-separator plate were then summed to calculate the contact resistance.

Referring to Table 1 and FIG. 2, contact resistance and corrosion current increased when deposition was performed at a temperature higher than 200 ° C, and there was a possibility that the coating layer could be peeled off due to the internal residual stress of the carbon coating material. In addition, contact resistance and corrosion current were higher than those deposited at 100 ℃ or higher in the case of deposition at less than 100 ℃.

3 is a photograph showing the surface of the separator coated according to the respective deposition temperatures. Referring to FIG. 3, it can be seen that a homogeneous coating layer was formed when deposition was performed at 200 ° C. or lower.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, You will understand.

It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. The scope of the present invention is defined by the appended claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be interpreted as being included in the scope of the present invention .

10: reaction chamber
11: Electrode
12: Power supply
20: base metal

Claims (16)

Vaporizing a precursor comprising a compound represented by the following formula (1) to produce a precursor gas;
Introducing the precursor gas and the reactive gas into a reaction chamber; And
And applying a voltage to the reaction chamber to change the precursor gas and the reactive gas into a plasma state to form a coating layer on the base material.
[Chemical Formula 1]

(Wherein R ¹ to R ⁸ are each independently a substituted or unsubstituted C1 to C10 alkyl group,
Wherein N is nitrogen,
Wherein Me is Ti, Cr, Mo, W, Cu, or Nb.
The method according to claim 1,
Wherein the precursor further comprises a compound represented by the following Formula 2,
Wherein the compound represented by Formula 1 is different from the compound represented by Formula 2 below.
(2)

(Wherein R ⁹ to R ¹⁶ are independently a substituted or unsubstituted C1 to C10 alkyl group,
Wherein N is nitrogen,
Wherein Me is Ti, Cr, Mo, W, Cu, or Nb.
The method according to claim 1,
Wherein each of R ¹ to R ⁸ is a methyl group (CH ₃ ).
4. The method according to any one of claims 1 to 3,
Wherein the step of forming a coating layer on the base material is performed at a temperature of 200 DEG C or less.
5. The method of claim 4,
Wherein the step of vaporizing the precursor to produce a precursor gas is performed at a temperature ranging from 50 to 80 캜.
6. The method of claim 5,
The reactive gas may be a hydrocarbon gas; Inert gas; And a separator plate coating method for a fuel cell, which is a nitrogen compound gas or a nitrogen gas.
The method according to claim 6,
The hydrocarbon gas is a material selected from C ₂ H ₂ , CH _4, or a combination thereof,
The inert gas is Ar,
Wherein the nitrogen compound is NH ₃ .
4. The method according to any one of claims 1 to 3,
Further comprising the step of imparting a hydrophobic group or a hydrophilic group after the step of forming the coating layer on the base material by changing the precursor gas and the reactive gas into a plasma state.
9. The method of claim 8,
The step of imparting the hydrophobic group or the hydrophilic group comprises:
A gas selected from the group consisting of CF ₄ , O ₂ , CO ₂ , polydimethylsiloxane (PDMS), trimethylsilyl (TMS), or a combination thereof is converted into a plasma state, Si, or a combination thereof.
A separator for a fuel cell and a coating layer disposed on one or both surfaces of the separator for a fuel cell,
The coating layer may include carbon having an SP2 structure; And
A nitride of a material selected from Ti, Cr, Mo, W, Cu, Nb, or a combination thereof.
11. The method of claim 10,
Wherein the coating layer is a nitride of a material selected from the group consisting of Ti, Cr, Mo, W, Cu, Nb, or combinations thereof, the content range of the carbon having the SP2 structure is 40% to 70% .
The method according to claim 10 or 11,
Wherein the thickness of the coating layer is 20 nm to 1000 nm.
13. The method of claim 12,
Wherein the coating layer further comprises a material selected from the group consisting of F, O, Si, or combinations thereof.
A precursor for a fuel cell separator comprising a compound represented by the following formula (1).
[Chemical Formula 1]

(Wherein R ¹ to R ⁸ are each independently a substituted or unsubstituted C1 to C10 alkyl group,
Wherein N is nitrogen,
Wherein Me is Ti, Cr, Mo, W, Cu, or Nb.
15. The method of claim 14,
Wherein the precursor further comprises a compound represented by the following Formula 2,
Wherein the compound represented by Formula (1) and the compound represented by Formula (2) are different from each other.
(2)

(Wherein R ⁹ to R ¹⁶ are independently a substituted or unsubstituted C1 to C10 alkyl group,
Wherein N is nitrogen,
Wherein Me is Ti, Cr, Mo, W, Cu, or Nb.
15. The method of claim 14,
Wherein R ¹ to R ⁸ are both pre-cursor methyl group (CH ₃₎ separate the fuel cells panyong.

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